1. Field of the Invention
The invention relates to a three-dimensional display device, and in particular, an integral photography type three-dimensional display device.
2. Discussion of the Related Art
A two-dimensional display device is generally used. Recently, because of wideband communication networks, a three-dimensional display device has been researched and developed.
There are various types of three-dimensional image displays, for example, a holographic image type, a stereographic type, a volumetric type and the like.
The holographic type is used for a holographic image using a laser or a white ray.
The stereographic type display device displays a three-dimensional image using binocular parallax. The stereographic type display device includes a display device that uses specific glasses and a display device without glasses. The stereoscopic display devices without glasses are divided into a parallax barrier type, a lenticular type, and the like.
The volumetric type is used for three-dimensional computer graphics or an I-MAX movie. Of volumetric types, an integral photography type has advantage of identically reproducing optical properties, such as light distribution and brightness, of a real three-dimensional object and displaying a three-dimensional image perceived as the real three-dimensional object.
FIGS. 1A and 1B are views illustrating a principle of displaying a three-dimensional image in an integral photography type three-dimensional display device.
Referring to FIG. 1A, when there is a real three-dimensional object 50, the object 10 is perceived through rays 10a to 10f emitted from a surface of the object 10. In other words, external rays reflecting on the object 10 or rays radiating at the object 10 itself are emitted as the rays 10a to 10f from the object 10, and a viewer combines the rays 10a to 10f and perceives the object 10.
Referring to FIG. 1B, if a three-dimensional display device emits rays 20a to 20f which have the same light distribution and brightness as the rays 10a to 10f emitted from the surface of the object 10, the viewer combines the rays 20a to 20f from the display device and perceives a virtual object 20 as the object 10.
FIG. 2A is a view illustrating an image-taking device, and FIG. 2B is a view illustrating an integral photography type three-dimensional display device according to the related art.
Referring to FIG. 2A, the image-taking device 60 includes an image-taking lens array 62 and an image-taking panel 64. The image-taking lens array 62 includes a plurality of convex lens in a matrix form. The image-taking panel 64 has a plurality of pixels. The image-taking panel 64 uses a photograph for static images, and a CCD (charge-coupled device) for moving images.
An object 50 emits a plurality of rays 50a toward the image-taking lens array 62, and the rays 50a is condensed through the image-taking lens array 62 and recorded in the pixels of the image-taking panel 64.
The plurality of pixels of the image-taking panel 64 records a plurality of images 52 of the object viewed through the plurality of convex lens of the lens array 62, respectively. Accordingly, the image-taking device 60 takes image data for the object 50 viewed in various directions in space.
The image data are displayed by the integral photography type three-dimensional display device of FIG. 2B and combined by a viewer, and a three-dimensional image is perceived.
Referring to FIG. 2B, the integral photography type three-dimensional display device 70 includes a display panel 72 and a display lens array 74. The display panel 72 includes a plurality of pixels. The display panel 72 uses a photograph for static images, and a flat display panel for moving images. The display lens array 74 includes a plurality of convex lens in a matrix form in similar to the image-taking lens array 62.
The display panel 72 is supplied with the image data recorded by the image-taking device 60. The plurality of pixels of the display panel 72 display the plurality of images 52 of the object 50, respectively, using the image data. A plurality of rays 74 emitted from the plurality of pixels of the display panel 72 are condensed through the plurality of convex lens of the display lens array 74. The condensed plurality of rays 80a form a plurality of voxels (volume pixels). A plurality of partial images displayed at the plurality of voxels are integrated at a point and form an image 80 corresponding to the object 50 at a certain position in space.
Through these processes, the integral photography type three-dimensional display device 70 displays the three-dimensional image 80 identical to the object 50, and the viewer perceives as if the object 50 existed.
Because the integral photography type three-dimensional display device forms three-dimensional images in space, the integral photography type three-dimensional display device supplies continuous horizontal and vertical parallax, and single or multiple viewers view the three-dimensional images without specific glasses. However, because position of the voxels formed in space through the lens array is fixed, a depth range given to the displayed image is limited. This limitation is because the lens array of a passive lens type is used.
In other words, the lens array is fixed in the related art integral photography type three-dimensional display device, and position and property of the convex lens of the lens array is fixed. Accordingly, condensing direction and condensed position by the lens array is not actively control, and thus the depth range given to the displayed image is limited.